This proposal focuses on the role of inflammation in the pathogenesis of and therapeutic options for amyotrophic lateral sclerosis (ALS) using transgenic mice expressing the glycine-93--> arginine mutant copper/zinc superoxide dismutase (SOD1G93A). Pertinent to this goal, first, we have shown that content of pro-inflammatory prostaglandin PGE2 is increased in spinal cords of affected transgenic SOD1 G93A mice. To elucidate the role of PGE2-synthesizing enzyme, cyclooxygenase-1 (Cox-1) in this model of ALS, Specific Aim (SA)-I will determine the effect of Cox-1 inhibition and ablation on mutant SOD1-mediated neurodegeneration. Second, we have evidence that the reactive oxygen species-producing microglial enzyme NADPH-oxidase is activated in spinal cords of affected transgenic SOD1G93A mice. To acquire a better understanding of the cytotoxic role of NADPH-oxidase in this model of ALS, SA-II will (1) define spinal cord expression of NADPH-oxidase subunits, at different disease stages in different lines of transgenic mice that express either mutant or wild-type SOD1; and (2) assess the effect of NADPH-oxidase deficiency on mutant SOD1- mediated neurodegeneration. Third, in the spinal cords from affected transgenic SOD1G93A mice, we have observed a robust activation of microglial cells, which may lead to the release of cytotoxic factors. To elucidate whether microglial activation is instrumental in mutant SOD1-mediated neurodegeneration, SA-III will assess the effects of the inhibition of microglial activation on spinal cord inflammatory response and neurodegeneration in transgenic mutant SOD1 mice. Fourth, vaccination of transgenic mutant SOD1 mice with the myelin basic protein-related peptide copolymer-1 (Cop-1) allows accumulation of activated T-cells in the diseased spinal cord which produce anti-inflammatory cytokines such as IL-4 and IL-10 and several neurotrophins. To examine whether such an immunization strategy can be beneficial in transgenic mutant SOD1 mice, SA-IV, will (1) determine the effect of Cop-1 vaccination on disease symptomatology, (2) assess the consequences of Cop-1 vaccination on spinal cord inflammatory response and neuropathology, (3) confirm the role of Cop-1 specific T-cells by adoptive transfer and their accumulation in both the central and peripheral nervous systems, and (4) demonstrate spinal cord production and cellular origin of IL-4 and IL-10 and neurotrophins, at different disease stages.